The invention concerns a wheeled shovel loader with the characteristics of-the generic portion of claim 1.
These types of shovel loaders, which travel on, for example, wheels or tracks, are well known and are widely used. These shovel loaders are particularly used for the loading of trucks with earth and building materials. During the loading of tall trucks or large dumping vehicles, particularly with lightweight bulk goods such as coal, coke, wood chips, garbage, etc., shovel loaders with a very large loading height are needed. These types of shovel loaders have available, for example, a shovel pivot point of at least 5 meters over the road level. In order to attain this loading height, there are, on one hand, very large shovel loaders with correspondingly tall hinged long booms with a corresponding unloaded weight and a large engine output (for example, 30 tons unloaded weight at 300 horsepower) for the loading of heavy goods. However, these shovel loaders are too large and too expensive for the loading of light goods. On the other hand, there are the so-called telescopic loaders with light material shovels, which are not very well liked in practice because they are relatively slow and very susceptible to wear and tear. The telescopes used in telescopic stackers run in slides which wear out when exposed to dust and dirt and higher sliding speeds, leading to breakdowns.
Proceeding from this, the invention has as its object the increasing of the loading height of a relatively small, mass-produced wheeled shovel loader in such a way that it is usable for the loading of tall trucks with light bulk goods without reduction of its stability.
To achieve this object, a shovel loader with the characteristics of claim 1 is suggested. According to this, the shovel loader has an additional arm, connecting the boom and the tool, which is hinged on the boom so as to be capable of displacement in the same way as a parallel linkage or parallelogram by means of a first connecting rod and a second connecting rod. When the boom is pivoted upward, extension of the entire boom is achieved by operation of the additional arm hinged on the boom. According to the invention, the shovel loader furthermore has means available for control of the position of the additional arm depending on the angle of the boom relative to the boom swivel pin. These means ensure that the additional arm is only extended from its position retracted onto the boom after a predetermined angle of the boom has been reached, thereby preventing an extension of the boom which impairs the stability of the shovel loader. Through the further means provided according to the invention for keeping the loading shovel parallel, goods in the loading shovel are prevented from falling out when the loading shovel is lifted.
In an embodiment of the invention, displacement of the additional arm from a position retracted onto the boom only occurs after the boom has passed through its horizontal position as it pivots upward. This ensures that extension of the entire boom only occurs above the horizontal position of the boom. Conversely, it is of course also ensured that, as the boom moves downward, the additional arm is completely folded in, at latest, before the boom passes through its horizontal position.
In an advantageous embodiment of the invention, the means for control of the displacement of the additional arm includes at least one angle sensor.
In another embodiment of the invention, the means for control of the displacement of the additional arm include at least one position sensor.
In a particularly advantageous embodiment of the invention, the additional arm for extension of the loading shovel is displaceable in an essentially horizontal direction even below the horizontal position of the boom, with the boom able to be shifted into a so-called floating position to adjust for the circular path of the loading shovel caused by the displacement of the additional arm. This measure allows the additional arm to be displaced forward in, for example, specific steering situations in which the shovel loader cannot be moved any nearer to the location of pickup and/or delivery of the goods to be moved. Before the boom can be lifted from this position, the additional arm must be completely retracted to maintain tipping resistance. For this purpose, an electric angle or position detector is advantageously provided for release of the hub movement by the boom.
In a further embodiment of the invention, the lengths of the first connecting rod and the second connecting rod are essentially equal.
In another embodiment of the invention, the first connecting rod is shorter or longer than the second connecting rod. Due to the unequal lengths of the first connecting rod and the second connecting rod, the end position of the additional arm in its completely folded out position can be influenced. If, for example, the first connecting rod, i.e., the connecting rod hinged on the boom further from the chassis, is shorter than the length of the second connecting rod, which is hinged on the boom closer to the chassis, the additional arm displays a relatively flat positioning in relation to the completely raised boom.
Further advantageous embodiments are described in the sub-claims.
Of course, the characteristics mentioned in the preceding and described in the following are not usable only in the combinations indicated, but also in other combinations or alone, without leaving the framework of the present invention.